#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface OrderAfterPeriodSelectNumView : UIView
//左边标题
@property (nonatomic,strong) UILabel *titleLab;
//数量
@property (nonatomic,strong) UILabel *numLab;

@end

#import "OrderAfterPeriodSelectNumView.h"
@interface OrderAfterPeriodSelectNumView()
@property (nonatomic, assign) CGFloat titleLabWidth;
@end

@implementation OrderAfterPeriodSelectNumView

#pragma mark - 原始初始化方法

// 1、首先调用init方法
- (instancetype)init{
    if (self = [super init]) {
        [self initUI];
    }
    return self;
}
  
// 2、然后调用initWithFrame方法
- (instancetype)initWithFrame:(CGRect)frame{
    if (self =[super initWithFrame:frame]) {
        [self initUI];
    }
    return self;
}
// 初始化UI控件
- (void) initUI{
    UILabel *titleLab = [[UILabel alloc] init];
    titleLab.textColor = [UIColor colorWithHexString:@"333333"];
    titleLab.font = [UIFont systemFontOfSize:14];
    titleLab.textAlignment = NSTextAlignmentLeft;
    titleLab.text = @"退款数量";
    [self addSubview:titleLab];
    _titleLab = titleLab;
    
    UILabel *numLab = [[UILabel alloc] init];
    titleLab.textColor = [UIColor colorWithHexString:@"333333"];
    numLab.font = [UIFont systemFontOfSize:14];
    numLab.textAlignment = NSTextAlignmentRight;
    numLab.text = @"0";
    [self addSubview:numLab];
    _numLab = numLab;
    //获取字符串的宽高
    CGRect rect = [titleLab.text boundingRectWithSize:CGSizeMake(SCREENWIDTH, MAXFLOAT) options:NSStringDrawingTruncatesLastVisibleLine | NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading attributes:@{NSFontAttributeName: [UIFont systemFontOfSize:14]} context:nil];
    _titleLabWidth = rect.size.width;

}
// 设置UI控件的frame
- (void)layoutSubviews{
    [super layoutSubviews];
    // 1.获取当前控件的尺寸
    CGFloat width = self.frame.size.width;
    CGFloat height = self.frame.size.height;
    
    // 2.设置子控件的frame
    self.titleLab.frame = CGRectMake(16, 0, self.titleLabWidth, height);
    self.numLab.frame = CGRectMake(16+self.titleLabWidth, 0, width - (16+self.titleLabWidth+16), height);
    
}

@end

添加到UIStackView

OrderAfterPeriodSelectNumView *numView = [[OrderAfterPeriodSelectNumView alloc] init];
[numView mas_makeConstraints:^(MASConstraintMaker *make) {
     make.height.equalTo(@(50));
 }];
self.numView = numView;
[self.stackView addArrangedSubview:numView];